The mechanical separation of mineral particles according to their specific gravity is achieved in a variety of ways including the process of jigging. In a conventional jig, particles in a thick suspension in a slurry are repeatedly allowed to fall, stratifying the particles into layers which are then removed.
The efficient operation of such equipment requires sizing of the feed product, and particles of small size which inevitably are produced in crushing and milling, cannot be recovered by normal processing. Such smaller particles in wet processing become what is termed "slimes", and the forces available to shear these particles from the viscous fluid and to separate them from large particles of lower specific gravity are, in prior art processes, inadequate.
An essential characteristic of the jigging process is repetitive acceleration of the particles, separation occurring due to the fact that the heavy particles have a greater initial acceleration and speed than the light particles. In the case of small particles furthermore, these must have sufficient acceleration also to overcome fluid resistance, which is of great significance in the case of particles having a large surface area, for example gold particles which have been flattened in the grinding process.